###### Alissa Fong

MA, Stanford University
Teaching in the San Francisco Bay Area

Alissa is currently a teacher in the San Francisco Bay Area and Brightstorm users love her clear, concise explanations of tough concepts

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# Solving a Rational Equation - Problem 6

Alissa Fong
###### Alissa Fong

MA, Stanford University
Teaching in the San Francisco Bay Area

Alissa is currently a teacher in the San Francisco Bay Area and Brightstorm users love her clear, concise explanations of tough concepts

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If you have a fraction = another fraction, we call that a proportion. We can solve proportions using what's called "cross multiplication," or setting the product of diagonal numerators and denominators equal. Technically, what we're doing in this case is multiplying both sides by the reciprocal of one of the fractions, which makes it mathematically valid. Don't forget to include positive and negative solutions if you are taking square roots to solve for x, and don't forget to make sure all of your solutions are in the domain! (That is, make sure none of your solutions would make the denominator of one of your fractions zero.)

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